1. Field
This invention is in the field of velocipeds (pedal-powered wheeled vehicles) and motorcycles, related to their axle fastening hardware.
2. Prior art
Wheel axles are attached to a bicycle frame by various means. Threaded nuts are the simplest, but require wrenches, making them inconvenient and slow. They are subject to loosening or stripped threads, which can cause loss of control while riding.
Quick-release axle fasteners allow attachment and removal of a wheel axle without tools. This speeds the repair of flat tires, and simplifies the partial disassembly of bicycles for storage and transport. However, prior quick-release fasteners are subject to accidental release from impacts or improper operation. Common operation errors are: incomplete rotation of the cam lever; misalignment of the axle; and misadjustment of clamping tension of the fastener. Most quick-release axle fasteners require a hollow axle, and include a control rod passing through the axle. This rod can be overstressed if the tension of the fastener is too high. It then breaks, instantly disengaging the axle from the frame. If clamping tension is too low, the axle slips out of alignment or disengages from the frame. These mistakes cause accidents. Thus, the advantages of quick-release hubs have been offset by critical disadvantages. Variations of the lever-operated clamping design have been developed with safety in mind, but they all have weaknesses.
The quick-release hub of U.S. Pat. No. 4,400,038 (Hosokawa) has a safety mechanism which prevents axle release until the cam lever is fully rotated. However, in the partly rotated position, it is susceptible to release from impacts. The present invention is safer, since it requires the release of two levers and two slides, and the slides are not susceptible to impacts. Hosokawa has a higher number of different parts than the present invention, including a hollow axle and control rod, which are expensive.
The quick-release hub of U.S. Pat. No. 4,964,287 (Gaul) uses a cam with a removable lever or key for security. The key or lever can be lost. The cam position is hidden, so the user could assume the cam is engaged when it is not. Gaul has a higher number of different parts than the present invention, but no safety interlock. His lock-down washers 26, 28 do not serve this function, since they do not hold the axle in the drop-out when the cam is released. Thus, the present invention is safer, yet simpler. The quick-release hub of U.S. Pat. No. 4805941 (Segawa, FIGS. 4, 5) offers a safety interlock. His clamping mechanism needs enough range to fully relax the spring 6 of the interlock, since no radial lip is provided for its disengagement from the drop-out with the fingers. Thus, his interlock is inactive when it is needed most, in the released position of the cam lever. When partially rotated, his cam lever is releasible by impact or vibration, defeating the safety. The safety interlock in the present invention protects even in the fully released position of the cam lever. The quick-release hub of U.S. Pat. No. 4,805,941 (Downing) has a safety hook for holding the axle in the drop-out. However, it requires a specialized drop-out with the hook assembly, it can be released by impacts, is vulnerable to damage, and engagement of the hook is optional. The present safety uses conventional drop-outs, will not release from impacts, is not vulnerable to damage, and the safety interlock is not optional.